The present invention relates to packet forwarding apparatuses and multicast expansion methods. Multicast expansion means searching for a plurality of destinations for a single multicast packet. The packet is duplicated for each of the plurality of destinations found. Then, the duplicated packets, which have the same contents, are distributed.
Services provided over IP networks, such as video distribution and voice-over-IP (VoIP) telephony, in which real-time performance is critical, are becoming more and more popular, and there are increasing demands to improve the quality of such services. In order to improve VoIP quality and multicast processing performance to realize efficient video distribution, quality-of-service (QoS) control is becoming increasingly important in routers and switches for reducing delay fluctuations. In order to reduce costs, for example, there are demands for an increased number of interfaces or users that can be accommodated by a single router or switch. Also, in order to support high-volume data communication such as video distribution services, there are demands to provide high-speed lines in routers and switches to achieve wire-rate processing.
A technology has been developed for realizing efficient multicast processing that has no input-bandwidth restriction, by performing one-time readout of a destination information table in multicast processing to finish multicast processing in the same cycle as unicast processing (for example, see FIG. 3 in Japanese Unexamined Patent Application Publication No. 2000-31983).